1. Field of the Invention
The invention relates to a method of implementing manual operations in a processor in which several programs are executed under time slice control.
2. Prior Art
Nearly all control of electronic data processing systems must be capable of carrying out manual operations for such systems. Manual operations, such as the address compare equal stop, the program stop or single cycle operations generally serve to test and maintain both the circuits and the programs currently executed on the machines.
By means of the address compare equal stop, which refers to instruction addresses, it can be monitored, for example, whether program branches prescribed by branch instructions have been actually carried out at the specified point in the program. Single cycle operations, for example, can be used to change individual instructions in a program, to withdraw them altogether, or to replace them by other instructions.
Known solutions for implementing such manual operations, which were controlled from the operator console of an electronic data processing system, generally operated in such a manner that the time control logic of the processor had to be accessed by means of control lines, in order to activate the manual operations required. These control lines are activated either manually by console switches or by a second processor which automatically activates the necessary control lines.
This technology has substantial disadvantages, since the circuits required to access the clock control are very expensive and since any stoppage of the clock for executing the manual operations in a time slice controlled multiprogram processor for a particular program leads to all the other programs being stopped and interrupted as well, so that much machine time is lost.